$ { \left[\begin{array}{rr}{-2} & {-1} \\ {4} & {1} \\ {2} & {1}\end{array}\right]-\left[\begin{array}{rr}{2} & {-1} \\ {1} & {2} \\ {1} & {4}\end{array}\right] = {?} } $
Explanation: To find the difference of two matrices, subtract the corresponding items between each matrix. ${\left[\begin{array}{rr}{-2}-{2} & {-1}-{-1} \\ {4}-{1} & {1}-{2} \\ {2}-{1} & {1}-{4}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{-4} & {0} \\ {3} & {-1} \\ {1} & {-3}\end{array}\right]}$